Welcome to the forum.
A few questions that may help somebody provide an answer:
Do the doors lock using the key or using the dash button, do they lock using the remote at a different location, do the doors try to lock and then unlock as if not all the doors are closed, is there a source of radio interference nearby such as an amateur radio aerial, phone mast, mobile phone always switched on, does the spare key work, is the car battery fully charged at 12.5 to 12.7 volts, are there any other problems with the car ?
Maybe the remotes need synchronising with the car (in the car handbook after replacing a battery and as below), possibly there is a problem with the comms 2000 unit (the big part below the steering wheel containing the light and wiper stalks) which has the remote receiver.
4. Synchronisation of HF PLIP remote controls
N.B. : When replacing the batteries of an HF PLIP remote control, it is necessary to resynchronise the remote control.
Perform the following operations :
- Put the HF key to be synchronised in position "ignition +"
- Within the next 10 seconds, press one of the HF key buttons
- Release the HF key button
The ignition key HF PLIP is synchronised.
N.B. : Perform these operations for the other keys equipped with HF remote control.
Carry out a locking / unlocking test of the vehicle’s doors and tailgate.
N.B. : If the locking / unlocking test of the doors and tailgate is not correct, restart the synchronisations of all the ignition keys equipped with HF PLIPS.